A Direct Sequence Spread Spectrum (DSSS) is a spread spectrum technique that spreads the original data signal into a certain sequence to thereby perform communication. The DSSS has been widely used in radio frequency (RF) communication systems.
FIG. 1 is a block diagram illustrating a configuration of a DSSS demodulator 100 according to a conventional art.
The DSSS demodulator 100 includes an analog-to-digital (A/D) converter 110, a decimator 120, a correlator 130, a deframer 140, a pseudo noise (PN) code generation unit 150, and a cyclic redundancy check (CRC) checker 160.
The A/D converter 110 may receive an analog signal from an outside and convert it to a digital signal. The decimator 120 may receive the converted digital signal and determine a decision point among the eight times over-sampled data. The correlator 130 may correlate between the determined signal and a PN code from the PN code generation unit 150 to thereby compare correlation property. When a correlation value is greater than or equal to a predetermined threshold, the deframer 140 may cancel a PN code that is added in a received signal to thereby deframe an original signal. The CRC checker 160 may perform CRC in order to determine whether the deframed original signal is normal.
In the DSSS modulating/demodulating process, a PN code with an excellent correlation property may need to be used in order to accurately demodulate the original signal. Therefore, there is a need for an apparatus that can generate the PN code with the excellent correlation property.